Resin end-face butt joint, method for welding the joints, and piping member

ABSTRACT

The present invention addresses the problem of providing a resin end-face butt joint, a method for welding the joints, and a piping member, with which it is possible to ensure a sufficient clamping margin with the clamp of an ordinary welding machine and to ensure an appropriate distance between the centers even when joints having short tubular welding ring parts are welded, and with which it is possible to align the centers by positioning the centers along the same axis. The device for solving this problem is a resin end-face butt joint for which multiple welding ring parts ( 13, 14 ) which communicate with a flow path ( 15 ) within a joint base part ( 12 ) are provided on the joint base part, and fastening parts ( 18, 19 ) are provided so as to be coaxial with at least one of these welding ring parts at the outer end of the joint, for the purpose of clamping a welding machine.

TECHNICAL FIELD

The present invention relates to a resin end-face butt joint, a methodfor welding the joints, and a piping member that are used in the fieldsof semiconductor industry, food industry, pharmaceutical industry,biotech industry, chemical industry, etc.

BACKGROUND ART

Piping materials used in the fields of semiconductor industry, foodindustry, pharmaceutical industry, biotech industry, chemical industry,etc. are required to have chemical resistance, heat resistance, highcleanliness, etc. For the piping materials satisfying theserequirements, fluorine resin, such as PFA (PerFluoroAlkoxyethylenecopolymer resin), is suitable.

Piping constituting manufacturing lines in these fields of industry iscomposed of joints made of thermoplastic resin including PFA resin orthe joint and a tube etc. to be butt welded at their respective endfaces in some cases.

When butt-welding the pipe end faces of joints or tubes etc.(hereinafter referred to as workpieces) made of thermoplastic resin,adopted is a welding method comprising coaxially positioning pipe endfaces of the workpieces disposed on the opposite sides of a heater in anon-contact state, heating the pipe end faces by heat of the heater tobe in an appropriate molten state and then thrusting the pipe end facesagainst each other.

As a device for welding the pipe end faces of the workpieces to eachother using this method, the welding machine of Patent Document 1 hasbeen known to the art. This welding machine 1 comprises, as shown inFIG. 9, a heater 2 on the opposite sides of which a pair of workpieces3, 3 to be welded in a non-contact state are disposed, and a pair ofclamps 5, 5 disposed on the opposite sides of the heater 2 fortightening and grasping the workpieces 3, 3, fixing the workpieces withan appropriate distance held so as not to bring pipe end faces 4, 4 ofthe workpieces 3, 3 into contact with the heater 2 at the time ofheating and melting, moving at least one of the pipe end faces coaxiallyafter the pipe end faces 4, 4 of the workpieces 3, 3 to be heated andmelted are brought to an appropriate molten state and thrusting the pipeend faces 4, 4 of the workpieces 3, 3 against each other to be welded

Introduced in Patent Document 2 is a welding method for weldingworkpieces to each other using such the welding machine to preventharmful inner face beads.

PRIOR ART DOCUMENT Patent Document

-   Patent Document 1: JP HEI 8-156102 A-   Patent Document 2: JP 2004-216859 A

SUMMARY OF THE INVENTION Problems the Invention Intends to Solve

In the welding machine of Patent Document 1 and welding method of PatentDocument 2, when welding ring parts of a resin joint are short in lengthand have a short cylindrical shape, since it is impossible to ensure asufficient clamping margin for tightening and fixing the welding ringparts with clamps, it is impossible to tighten and fix the welding ringparts with the clamps and it is necessary to fix the resin joint per seto the welding machine using a special jig for fixing. However, use ofthe special jig for fixing to fix the resin joint to the welding machinemakes the laying operation cumbersome, takes much time to align thecenters of the pipe end faces of the joints and possibly inducesposition aberration at the welding parts of the joints. Proposal of aresin joint capable of solving these problems, melting by heat the pipeend faces with high precision to be welded to each other has beenanxious to.

The present invention has been developed in order to solve theaforementioned problems and the object thereof is to provide a resin endfact butt joint, a method for welding the joint, and a piping member,with which it is possible to ensure a sufficient clamping margin withthe clamp of an ordinary welding machine and to ensure an appropriatedistance between the centers even when joints having short tubularwelding ring parts are welded, and with which it is possible to alignthe centers by positioning the centers along the same axis.

Means for Solving the Problems

To attain the above object, the invention according to claim 1 relatesto a resin end-face butt joint comprising a joint base part providedtherein with a flow path, multiple welding ring parts provided on thejoint base part and communicating with the flow path in the joint basepart, and fastening parts provided at an outer end of the joint basepart for clamping a welding machine so as to be coaxial with at leastone of the welding ring parts.

The invention according to claim 2 relates to the aforementioned resinend-face butt joint, wherein the welding ring parts have a short tubularshape, and the fastening parts coaxial with the welding ring parts havea circular shape having an outside diameter identical with an outsidediameter of the welding ring parts.

The invention according to claim 3 relates to the aforementioned resinend-face butt joint, wherein the welding ring parts provided on thejoint base part have any one of shapes consisting of an elbow shape, aT-shape and an angled T-shape.

The invention according to claim 4 relates to a method for welding resinend-face butt joints, comprising projectingly forming circular fasteningparts integrally on an outer end of a joint base part so as to becoaxial with welding ring parts provided on the joint base part,tightening and grasping the fastening parts with a clamp of a weldingmachine, heating and melting end faces of the welding ring parts with anon-contact heater, and thrusting the welding ring parts against eachother to weld the end faces to each other.

The invention according to claim 5 relates to the aforementioned methodfor welding resin end-face butt joints, wherein the fastening parts ofthe resin joints are tightened and grasped with the clamp and the methodcomprises shortest welding that welds the welding ring parts having ashort tubular shape at a shortest core interval dimension.

The invention according to claim 6 relates to the aforementioned methodfor welding resin end-face butt joints, wherein workpieces are welded toeach other, one of which is an end face of the welding ring part havingthe short tubular shape and having the fastening parts tightened andgrasped with the clamp and the other of which is an end face of a tube,a pipe end face of a mechanical joint or a connection end face of avalve, a pressure or flow rate sensor or a filter.

The invention according to claim 7 relates to a piping memberconstructed through a welding method comprises fastening a resinend-face butt joint to a welding machine, with fastening parts tightenedand grasped with a clamp, wherein the resin end-face butt jointcomprises a joint base part provided therein with a flow path, multiplewelding ring parts provided on the joint base part and communicatingwith the flow path in the joint base part, and fastening parts providedat an outer end of the joint base part for clamping a welding machine soas to be coaxial with at least one of the welding ring parts.

Effects of the Invention

According to the invention set forth in claim 1, since tightening andfixing can be attained coaxially and at an appropriate core intervaldimension with the clamp of an ordinary welding machine without use of afixing jig, joints made of various kinds of thermoplastic resins andprovided with the welding ring part having the short tubular shape caninfallibly welded with ease. Particularly, it is possible to performshortest welding of two joints to each other, thereby enabling thedevice per se to be downsized and enabling remarkable contribution toreduction in size and compactness of a piping space.

According to the invention set forth in claim 2, since the fasteningpart has a circular shape of an outside diameter identical with theoutside diameter of the welding ring part, coaxial tightening and fixingcan be attained with the clamp of an ordinary welding machine withoutnecessitating a special jig. Furthermore, since a fixing margin that isthe length of the fixing width can sufficiently be secured, constructionproperty and workability are remarkably good.

According to the invention set forth in claim 3, the invention isapplicable to various kinds of joints having an elbow shape, T-shape,angled T-shape, etc.

According to the invention set forth in claim 4, even when the weldingring part has a short tubular shape and a dimension unable to secure thelength of the fixing margin, it is possible to provide a welding methodeasily enabling tightening and fixing with the clamp of an ordinarywelding machine, enabling fixing at an appropriate core intervaldimension, enabling coaxial retaining infallibly, enabling corealignment with ease without inducing a position gap.

According to the invention set forth in claim 5, since two joints eachprovided with the welding ring part having a short tubular shape can bewelded to each other with exactitude, a joint member having a shortestcore interval dimension can easily be constructed to contributeremarkably to compactness.

According to the invention set forth in claim 6, not only two joints,but also a joint and a tube or mechanical joint or a joint and aworkpiece such as a valve can infallibly be welded to each other, withthe fastening part of the joint provided with the welding ring parthaving the short tubular shape tightened and fixed.

According to the invention set forth in claim 7, since it is possible toprovide a piping member having two joints, a joint and a tube ormechanical joint, or a joint and a workpiece such as a valve welded toeach other, it is possible to downsize a drug solution providing device,for example, and to reduce in piping space, thereby enabling remarkablecontribution to compactness and enabling stable welding working to beperformed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an elbow-shaped joint of a resinend face butt joint according to the present invention.

FIG. 2 is a cross section of FIG. 1.

FIG. 3 is an explanatory front view showing a state in which the jointsof FIG. 1 are welded to each other in a shortest distance.

FIG. 4 is an enlarged front view showing a piping member having thejoints of FIG. 3 welded to each other.

FIG. 5 is a perspective view showing a T-shaped joint of the resin endface butt joint according to the present invention.

FIG. 6 is a perspective view showing an angled T-shaped joint of theresin end face butt joint according to the present invention.

FIG. 7( a) is an explanatory view showing a state in which a jointhaving short tubular shaped welding ring parts and an elbow joint arewelded to each other, FIG. 7( b) is an explanatory view showing a statein which a joint having short tubular shaped welding ring parts and atube are welded to each other, FIG. 7( c) is an explanatory view showinga state in which a joint having short tubular shaped welding ring partsand a pipe of a valve are welded to each other, and FIG. 7( d) is anexplanatory view showing a state in which a joint having short tubularshaped welding ring parts and a pipe of a mechanical joint are welded toeach other.

FIG. 8 is an explanatory view showing a state in which fastening partsof the joint in the present invention are tightened and grasped with anexclusive jig for press fit of a sleeve and the sleeve is press-fitconstructed.

FIG. 9 is a view showing a state in which conventional resin joints tobe welded to each other are tightened and grasped with clamps.

MODE FOR CARRYING OUT THE INVENTION

An embodiment of the resin end-face butt joint according to the presentinvention will be described in detail hereinafter with reference to thedrawings. FIGS. 1 and 2 show an elbow-shaped joint of the resin end-facebutt joint according to the present invention, FIG. 1 being aperspective view of the joint seen from obliquely upward and FIG. 2being a cross section of the joint.

The resin joint is made of thermoplastic resin. The thermoplastic resinincludes fluorine resins including PFA, PTFE, FEP, ETFE, PVDF, PVF,PCTFE and ECTFE, vinylidene chloride, vinyl chloride, vinyl acetate,polyvinyl alcohol, styrol, ABS, polycarbonate, polyethylene,super-high-molecular polyethylene, polypropylene, acryl, butyrate,acetate, polyamide, polyacetal, AS, vinylidene fluoride, etc. The resinend-face butt joint in the present invention is made of PFA.

In FIG. 1, an elbow-shaped joint 11 of the resin end-face butt jointcomprises a joint base part 12 provided therein with a flow path 15, awelding ring part 13 for welding a workpiece and a short tubular weldingring part 14.

The joint base part 12 is provided on the outer ends thereofrespectively with projecting fastening parts 18, 19 to be tightened andgrasped with clamps of a welding machine, which are coaxial respectivelywith central axes 16, 17 of the welding ring parts 13, 14.

The welding ring parts 13, 14 are provided to begin at the joint basepart 12. The welding ring parts 13, 14 are provided therein with flowpaths 20, 21, and the flow parts 20, 21 communicate with the flow path15 formed in the joint base part 12.

In the figure, the welding ring part 13 is formed in the long tubularshape and the welding ring part 14 is in the short tubular shape. Theconstruction of the joint 11 is not limited to this configuration. Forexample, both the welding ring parts 13, 14 may be formed in the longtubular shape and, in use, appropriately selected one of the weldingring parts may be cut to a predetermined short length. Otherwise, boththe welding ring parts 13, 14 may be formed in the short tubular shape.

The fastening parts 18, 19 provided on the outer ends of the joint basepart 12 are circular in shape and have their outside diameters 22, 23identical with outside diameters 24, 25 of the welding ring parts 13,14. While it is necessary that the projecting fastening parts 18, 19have circular cylindrical circumferences for being infallibly tightenedand grasped with the clamps of the welding machine, it is not alwaysnecessary that tops 26, 27 of the fastening parts 18, 19 have flatsurfaces. For example, as shown by a two-dot chain line 28 at thefastening part 19 in FIG. 2, the top of the fastening part 19 may beformed with a concave. That is to say, in this case, it becomes possibleto result in material saving and weight reduction.

The joint 11 in the present embodiment is formed under the samestandards as the conventional resin joint except that the joint basepart is provided at the outer ends thereof with the fastening partscoaxial with the welding ring parts 12, 13. However, this is notlimitative. Incidentally, in the present embodiment, the nominaldiameter of the welding ring parts 12, 13 is set to be 25.4 mm (1 inch).

It is necessary that the fastening parts 18, 19 have sufficient heightfor the purpose of being infallibly tightened and grasped with theclamps of the welding machine. The fastening margin generally falls inthe range of 6 to 15 mm. However, it is unnecessary that heights 29, 30of the fastening parts 18, 19 are set to be equal to the width of theclamps. The heights capable of infallibly fastening the joint withoutbeing wobbled when the fastening parts have been tightened and graspedwith the clamps will suffice.

Even when the height of the fastening part is set to be sufficientlysmaller than the size of the entire joint, since the joint caninfallibly be tightened and grasped with clamps, projections produced onthe outside of the joint base part can be minimized. For this reason,since the fastening parts do not interfere with other workpieces,compact piping can be constructed.

In addition, since the fastening parts are disposed on the outer ends ofthe joint base part, since the distance from the surface of the heaterto the fastening parts is not so different from the distance from thesurface of the heater to the clamp tightening and grasping part of thewelding ring part in the case of welding the conventional joints,appropriate dimension between the centers is secured.

Since the outside diameter 22, 23 of the fastening parts 18, 19 areidentical with the outside diameters 24, 25 of the welding ring parts13, 14, the clamps capable of tightening and grasping the welding ringparts 13, 14 can be used as-is. Therefore, when using resin end-facebutt joint, it is unnecessary to newly prepare clamps different in sizefrom the conventional clamps.

As shown in FIG. 2, since the fastening part 18 of the joint 11 isprojectingly disposed on the outer end of the joint base part 12 so asto be coaxial with the center axis 16 of the welding ring part 13 andhave the circular shape having the outside diameter identical with theoutside diameter 24 of the welding ring part 13, the positional relationbetween the welding ring part 13 and the welding machine when thefastening part 18 has been tightened and grasped with the clamp of thewelding machine is the same as the positional relation between thewelding ring part 13 and the welding machine when the welding ring part13 has been tightened and grasped with the clamp.

In the welding machine, when the workpiece to be welded is tightened andgrasped with the clamp, since it is set that the central axis of theworkpiece be coincident with the shaft center of the welding machine,when the fastening part 18 of the joint 11 has been tightened andgrasped with the clamp, the central axis 16 of the welding ring part 13in which the fastening part is coaxial with the center axis iscoincident with the shaft center of the welding machine.

The aforementioned relationship is retained in respect of the fasteningpart 19 disposed on the outer end of the joint base part 12 so as to becoaxial with the central axis 17 of the welding ring part 14.

Therefore, even when the welding ring part 14 unable to secure afastening margin of the clamp due to the short tubular shape is weldedto the workpiece, merely by tightening and grasping the fastening part19 with the clamp, the welding ring part 14 can be attached to thewelding machine, with the central axis 17 of the welding ring part 14 inalignment with the shaft center, thus enhancing the workabilityremarkably.

In addition, when the workpiece is welded to a short tubular weldingring part like the welding ring part 14, since the beads of the weldingpart can be positioned in the vicinity of the resin joint, the beads donot hinder the attachment of a piping support, sensor, etc. tocontribute to compactness of the piping

Furthermore, since the fastening parts 18, 19 have a circular shape, asshown in FIG. 1, distances 35, 36 between central axes 31, 32 of thefastening parts 18, 19 and outer circumferences 33, 34 of the fasteningparts are constant. Accordingly, when tightening and grasping thefastening part 19 with the clamp and welding the workpiece to an endpart 37 of the welding ring part 14, even in the case where the weldingring part 13 is rotated about the central axis 17 and the fastening part19 is tightened and grasped with the clamp, with an end part 38 of thewelding ring part 13 directed in any direction, the central axis 17 ofthe welding ring part 14 coaxial with the fastening part is coincidentwith the shaft center of the welding machine.

Therefore, even when the resin joint 11 is rotated about the centralaxis of the welding ring part 14 by an appropriate angle relative to theworkpiece to be welded, since a central axis of the workpiece to bewelded is in agreement with the central axis of the welding ring part 14of the resin joint 11, no crisscross is induced in the welding part. Forthis reason, since the resin joint 11 can be welded to the workpiece tobe welded at an voluntary rotation angle without limitation to a weldingangle, it is possible to compactly construct the piping, with the lengthof the piping to be used set to be minimum and to arbitrarily weld thejoint having free directionality.

In FIG. 3 and FIG. 4, when two resin joints 11 are welded to each otherat the welding ring parts 14 having a short tubular shape, the resinjoints 11 can be welded to each other at a shortest core intervaldimension. In this case, since it is impossible to tighten and grasp thewelding ring part 14 of the resin joint 11 with the clamp, as shown inFIG. 3, by grasping the outer circumference 34 of the fastening parts19, 19 of the resin joints 11, 11 with a grasping surface 40 of a clamp39, it is possible to fix the end parts 37, 37 of the welding ring parts14, 14 face-to-face in a non-contact state relative to a heater 42 of awelding machine 41 on the opposite sides of the heater 42. At this time,the center axes of the welding ring parts 14, 14 of the pair of resinjoints 11 are in agreement with each other as described earlier bysimply tightening and grasping the fastening parts 19, 19 of the resinjoints 11, 11 with the clamps 39, 39.

Shown in FIG. 4 is a piping member 43 prepared by welding the resinjoints 11 to each other at the shortest core interval dimension. Thus,since the piping member can be formed at the shortest core intervaldimension, use of the piping member 43 enables the piping of a device tobe compactly constructed.

In addition, since it is possible to weld the welding ring parts 14, 14to each other with their central axes in perfect agreement with eachother, it is possible to simply manufacture a high-quality piping memberwithout forming any difference in level on a welded part 45, hinderingliquid smooth flowing, producing a pool of liquid and inducing detentionand detachment of particles.

The present invention is not limited to the application to theelbow-shaped resin joint 11 of the present embodiment, but is applicableto a joint comprising a joint base part provided therein with a flowpath, multiple welding ring parts provided on the joint base part andcommunicating with the flow path in the joint base part, and fasteningparts provided at an outer end of the joint base part for clamping awelding machine so as to be coaxial with at least one of the weldingring parts. For example, the present invention is, of course, applicablesimilarly to a T-shaped joint 46 shown in FIG. 5 and an angled T-shapedjoint 47 shown in FIG. 6. In the T-shaped joint 46 of FIG. 5 and angledT-shaped joint 47 of FIG. 6, one of welding ring parts 48 has a shorttubular shape. Similarly to the case of the elbow-shaped joint 11,however, all the welding ring parts 48 may be formed in a long tubularshape and, in use, the welding ring parts 48 to be welded using afastening part 49 may be cut to a predetermined short length. Otherwise,all the welding ring parts 48 to be welded using the fastening part 49may be formed in a short tubular shape. Selection of any of these isarbitrary depending on exploitation.

Next, an example of a welding method of end-face butt joint in thepresent invention will be described.

At first, the joint 11 having the circular fastening part 19protrudingly provided integrally on the outer end of the joint base part12 so as to be coaxial with the welding ring part 14 provided on thejoint base part and a workpiece 50 to be welded to the joint 11 areprepared, the fastening part 19 of the joint 11 is fixed throughtightening and grasping with the clamp 39 of the welding machine 41 asshown in FIG. 3, and the workpiece 50 is simultaneously fixed throughtightening and grasping with the clamp 39 so that the joint andworkpiece 50 are disposed face-to-face across the heater 42 of thewelding machine 41.

The end part 37 of the joint 11 to be welded and an end face 51 of theworkpiece 50 to be welded are heated in a state of non-contact with theheater to be melted. After the end part 37 of the joint 11 and the endface 51 of the workpiece 50 are sufficiently melted by heat, the endpart and end face are thrust against each other to be welded to eachother.

In the welding method of the end-face butt joint according to thepresent invention, even when it is impossible for the welding ring part14 of the joint 11 to secure a fixing margin for tightening and securingwith the clamp 39, it is unnecessary to prepare an exclusive jig fortightening and grasping the joint per se as in the conventional weldingmethod and, by tightening and grasping with the conventional clamp 39the fastening part 19 externally provided on the joint base part 12 soas to be coaxial with the welding ring part 14 to be welded, the joint11 can be fixed to the welding machine 41, thus enhancing the workingefficiency remarkably.

In addition, when the fastening part 19 provided on the outer end of thejoint base part 12 is tightened and grasped with the clamp 39 so as tobe coaxial with the welding ring part 14 to be welded, the welding ringpart 14 can be fixed, with the centers thereof and the welding machine41 in alignment with each other. Therefore, it is unnecessary to performthe cumbersome center alignment having conventionally taken a long time,and the welding working of the joint can accurately be performed for ashort period of time.

The substantial difference between the case where the end-face buttresin joint of the present invention is welded by the welding method ofthe present invention and the case where the conventional resin joint iswelded by the conventional welding method is only the step of thepresent invention that tightens and grasps the fastening part of theend-fact butt resin joint with the clamp and fixes it to the weldingmachine. The remaining steps have no difference from those in the casewhere the conventional resin joint is welded by the conventional weldingmethod. Therefore, any worker mastering the conventional welding methodcan perform the welding working without receiving any working trainingand rather simply and infallibly using the conventional welding machineand clamp, resulting in extremely growing in economical value.

The above-described joint welding method is not limited to welding ofthe end-face butt joint of the present invention to a specificworkpiece, but is applicable to welding thereof to various workpieces asdescribed next.

When a joint 52 provided with the welding ring part having a shorttubular shape and an elbow-shaped joint 53 are to be welded, as shown inFIG. 7( a), a fastening part 54 of the joint 52 provided with thewelding ring part having the short tubular shape is tightened andgrasped with a clamp 55 and a welding ring part 56 of the elbow-shapedjoint 53 having a long tubular shape is tightened and grasped with theclamp 55. The fastening part and the welding ring part are disposedface-to-face across a heater 57 and their end faces are heated andmelted, so that these may be welded to each other.

When a joint 58 provided with the welding ring part having a shorttubular shape and a tubular part, such as a tube or pipe (hereinafterreferred to as the “tube”) 59 are to be welded, as shown in FIG. 7( b),a fastening part 54 of the joint 58 provided with the welding ring parthaving the short tubular shape is tightened and grasped with the clamp55 and the tube 59 is tightened and grasped with the clamp 55 at anappropriate position. The fastening part and the tube are disposedface-to-face across a heater 57 and their end faces are heated andmelted, so that these may be welded to each other.

When the joint 52 provided with the welding ring part having the shorttubular shape and a tube 61 of a valve 60 are to be welded, as shown inFIG. 7( c), the fastening part 54 of the joint 52 provided with thewelding ring part having the short tubular shape is tightened andgrasped with the clamp 55 and the tube 61 of the valve 60 is tightenedand grasped with the clamp 55. The fastening part and the tube aredisposed face-to-face across the heater 57 and their end faces areheated and melted, so that these may be welded to each other.

When the joint 52 provided with the welding ring part having the shorttubular shape and a tube 63 of a mechanical joint 62 are to be welded,as shown in FIG. 7( d), the fastening part 54 of the joint 52 providedwith the welding ring part having the short tubular shape is tightenedand grasped with the clamp 55 and the tube 63 of the mechanical joint 62is tightened and grasped with the clamp 55. The fastening part and thetube are disposed face-to-face across the heater 57 and their end facesare heated and melted, so that these may be welded to each other.

The resin end-face butt joint and method for welding the joints,according to the present invention is not limited to welding of thejoints to each other, but can manufacture various piping members havingthe joint and a tube, the joint and the mechanical joint, the joint anda valve or various kinds of sensors or a filter welded to each other. Byusing an appropriately selected combination, since it is possible toeliminate the unnecessary welding ring part etc. of the joint andconstruct piping only of really necessary parts, it is possible torealize small-sized piping of a drug solution providing device etc., forexample.

In addition, as shown in FIG. 8, a fastening part 65 of a joint 64according to the present invention is used in a different manner fromthe present embodiment. That is to say, with the fastening part 65tightened and grasped with a clamp 66, a sleeve 69 can be inserted underpressure into a welding ring part 70. Furthermore, the fastening part 65can be pressed against and fixed to a flat abutting surface 68 of anexclusive sleeve jig 67 or the like. Since the joint 64 is stabilizedwithout being moved even when a force is applied to the joint at thetime of the pressure insertion of the sleeve 69, the sleeve 69 caneasily be inserted under pressure into the welding ring part 70, therebyenabling the workability to be enhanced. Incidentally, reference numeral71 in the figure denotes a union nut.

As described in the foregoing, the case of welding the resin joint ofthe present invention using the welding method of the present inventionnot only enables the welding working to be efficiently and accuratelyperformed in comparison with the case of welding the conventional resinjoint using the conventional welding method, but also unnecessitates anew working training. In addition, since welding working can beperformed with the conventional welding machine and clamp, no economicalload is exerted to extremely enhancing the industrial utility value andeconomical value.

EXPLANATION OF REFERENCE NUMERAL

-   -   11 elbow-shaped joint    -   12 joint base part    -   13, 14, 49, 69 welding ring parts    -   18, 19, 54, 65 fastening parts    -   39 clamps    -   41 welding machine    -   42 heater    -   43 piping member    -   46, 64 T-shaped joints    -   48 angled T-shaped joint

1. A resin end-face butt joint comprising a joint base part providedtherein with a flow path, multiple welding ring parts provided on thejoint base part and communicating with the flow path in the joint basepart, and fastening parts provided at an outer end of the joint basepart for clamping a welding machine so as to be coaxial with at leastone of the welding ring parts.
 2. A resin end-face butt joint accordingto claim 1, wherein the welding ring parts have a short tubular shape,and the fastening parts coaxial with the welding ring parts have acircular shape having an outside diameter identical with an outsidediameter of the welding ring parts.
 3. A resin end-face butt jointaccording to claim 1, wherein the welding ring parts provided on thejoint base part have any one of shapes consisting of an elbow shape, aT-shape and an angled T-shape.
 4. A method for welding resin end-facebutt joints, comprising projectingly forming circular fastening partsintegrally on an outer end of a joint base part so as to be coaxial withwelding ring parts provided on the joint base part, tightening andgrasping the fastening parts with a clamp of a welding machine, heatingand melting end faces of the welding ring parts with a non-contactheater, and thrusting the welding ring parts against each other to weldthe end faces to each other.
 5. A method for welding resin end-face buttjoints according to claim 4, wherein the fastening parts of the resinjoints are tightened and grasped with the clamp and the method comprisesshortest welding that welds the welding ring parts having a shorttubular shape at a shortest core interval dimension.
 6. A method forwelding a resin end-face butt joint according to claim 4, whereinworkpieces are welded to each other, one of which is an end face of thewelding ring part having the short tubular shape and having thefastening parts tightened and grasped with the clamp and the other ofwhich is an end face of a tube, a pipe end face of a mechanical joint ora connection end face of a valve, a pressure or flow rate sensor or afilter.
 7. A piping member constructed through welding the jointsaccording to claim
 1. 8. A resin end-face butt joint according to claim2, wherein the welding ring parts provided on the joint base part haveany one of shapes consisting of an elbow shape, a T-shape and an angledT-shape.
 9. A method for welding a resin end-face butt joint accordingto claim 5, wherein workpieces are welded to each other, one of which isan end face of the welding ring part having the short tubular shape andhaving the fastening parts tightened and grasped with the clamp and theother of which is an end face of a tube, a pipe end face of a mechanicaljoint or a connection end face of a valve, a pressure or flow ratesensor or a filter.
 10. A piping member constructed through welding thejoints according to claim
 2. 11. A piping member constructed throughwelding the joints according to claim
 3. 12. A piping member constructedthrough welding the joints according to claim
 4. 13. A piping memberconstructed through welding the joints according to claim
 5. 14. Apiping member constructed through welding the joints according to claim6.